Teleseismic Traveltime Tomography of the Crust and Upper Mantle Beneath the Southern U.S. Continental Margin

Date: 4/26/2019

Time: 11:00 AM

Room: Vashon

The southern U.S. continental margin records a rich tectonic history spanning over 1.2 Ga, including two complete Wilson cycles. However, due to a thick sediment cover, the paucity of significant local seismicity, and sparse instrumentation in place to record seismicity, details of the tectonomagmatic evolution of this passive margin remain poorly understood. These issues include the amount, pattern, and direction of continental extension, the influence of pre-existing tectonic features during rifting, and the location and extent of allochthonous terranes and their associated suture zones. The advent of USArray’s Transportable Array, a temporary network of seismic stations, offers the unique opportunity to address these issues, which are vital to better understand the lithospheric structure and tectonic history of this scientifically and economically significant continental margin. This study incorporates broadband seismic data from 1,640 stations collected during the interval 2008-2017. Arrival times of direct P and S phases are picked, using a multi-channel cross-correlation method, for teleseismic earthquakes with magnitudes > 5.0 located at epicentral distances of 30° to 90° and PKIKP phases from earthquakes with magnitudes > 6.0 at epicentral distances of 125°-180°. An iterated, nonlinear solution technique is used in which raypaths and travel times are re-computed and Frechet derivatives are recalculated between inversions.

Presenting Author: Alden Netto

Authors